The problem that the invention aims to resolve will be explained with reference to the following nonlimiting example. The electrical circuit is, for example, installed in a vehicle and can comprise an electric motor for the electrical propulsion of the vehicle. The vehicle also comprises a chassis.
When the electrical energy storage unit is recharged by the electricity network, the chassis is connected to the earth. Because of the presence of components, spurious or not, between the electrical circuit and the chassis, a common mode current can circulate from the circuit to the chassis and loop back via the earth into the electricity network.
Such a common mode current is hazardous for a user standing on the earth and leaning on the chassis of the vehicle.
Also, standards exist for limiting the value of the common mode current that is acceptable between the part of the electrical circuit downstream of a rectifier and the chassis. The European standards thus limit the maximum value of the common mode current to 3.5 mA at a frequency of 50 Hz.
To observe these standards, it is known practice to provide an isolating transformer between the part of the circuit downstream of the reactifier and the chassis. Such a transformer can be costly and its integration in a space that is already limited such as a vehicle can be difficult.
It is also known practice to use, to rectify the current, a component with controllable switches, such as a so-called PFC (Power Factor Corrector) component, and to implement particular strategies for the control of the switches. Such strategies can lead to an overheating of the switches and be very complex.
In the high frequency domain, the publication “A simplified active input EMI filter of common-mode voltage cancellation for induction motor drive” discloses an active filter making it possible to reduce the common mode current at high frequencies by injecting a voltage in series into the electricity network.
Also known from the application US 2004/0004514 is an active filter seeking to reduce the common mode current at high frequencies in the field of electromagnetic compatibility (EMC).